Dry powder cationic lipopolymeric nanomicelle inhalation for targeted delivery of antitubercular drug to alveolar macrophage

Pulmonary inhalation for disease treatment: Basic research and clinical translations

Pulmonary drug delivery has the advantages of being rapid, efficient, and well-targeted, with few systemic side effects. In addition, it is non-invasive and has good patient compliance, making it a highly promising drug delivery mode. However, there have been limited studies on drug delivery via pulmonary inhalation compared with oral and intravenous modes. This paper summarizes the basic research and clinical translation of pulmonary inhalation drug delivery for the treatment of diseases and provides insights into the latest advances in pulmonary drug delivery. The paper discusses the processing methods for pulmonary drug delivery, drug carriers (with a focus on various types of nanoparticles), delivery devices, and applications in pulmonary diseases and treatment of systemic diseases (e.g., COVID-19, inhaled vaccines, diagnosis of the diseases, and diabetes mellitus) with an updated summary of recent research advances. Furthermore, this paper describes the applications and recent progress in pulmonary drug delivery for lung diseases and expands the use of pulmonary drugs for other systemic diseases.

Formulation of Resveratrol-Loaded Polycaprolactone Inhalable Microspheres Using Tween 80 as an Emulsifier: Factorial Design and Optimization

Resveratrol (RSV) is a bioactive phytoconstituent that has potential applications in respiratory diseases. However, poor oral bioavailability is the major hurdle to its clinical use. In the present work, resveratrol-loaded polycaprolactone (PCL) inhalable microspheres (MSs) were formulated to improve their therapeutic potential. The inhalable microspheres were formulated using the emulsion-solvent evaporation method. In this research, inhalable resveratrol microspheres were prepared using Tween 80 in place of polyvinyl alcohol which formed insoluble lumps. A 3² factorial design was applied taking polymer (PCL) and emulsifier (Tween 80) as independent variables and drug loading (DL) and encapsulation efficiency (EE) as dependent variables. The DL and EE of the optimized formulation were found to be 30.6% and 63.84% respectively. The in vitro aerosolization study performed using the Anderson cascade impactor showed that the fine particle fraction (FPF) of optimized resveratrol polycaprolactone microspheres (RSV-PCL-MSs) blended with lactose, and RSV-PCL-MSs were significantly higher than those of the pure drugs. The MMAD_T (theoretical mass median aerodynamic diameter) of optimized RSV-PCL-MSs was found to be 3.25 ± 1.15. The particle size of microspheres was within the inhalable range, i.e., between 1 and 5 µm. The morphological analysis showed spherical-shaped particles with smooth surfaces. The in vitro release study showed sustained drug release from the microspheres for up to 12 h. The study concluded that resveratrol-loaded inhalable microspheres may be an efficient delivery system to treat COPD.

A review of formulations and preclinical studies of inhaled rifampicin for its clinical translation

Inhaled drug delivery is a promising approach to achieving high lung drug concentrations to facilitate efficient treatment of tuberculosis (TB) and to reduce the overall duration of treatment. Rifampicin is a good candidate for delivery via the pulmonary route. There have been no clinical studies yet at relevant inhaled doses despite the numerous studies investigating its formulation and preclinical properties for pulmonary delivery. This review discusses the clinical implications of pulmonary drug delivery in TB treatment, the drug delivery systems reported for pulmonary delivery of rifampicin, animal models, and the animal studies on inhaled rifampicin formulations, and the research gaps hindering the transition from preclinical development to clinical investigation. A review of reports in the literature suggested there have been minimal attempts to test inhaled formulations of rifampicin in laboratory animals at relevant high doses and there is a lack of appropriate studies in animal models. Published studies have reported testing only low doses (≤ 20 mg/kg) of rifampicin, and none of the studies has investigated the safety of inhaled rifampicin after repeated administration. Preclinical evaluations of inhaled anti-TB drugs, such as rifampicin, should include high-dose formulations in preclinical models, determined based on allometric conversions, for relevant high-dose anti-TB therapy in humans.

Challenges and Opportunities of Nanotechnological based Approach for the Treatment of Tuberculosis

Mycobacterium tuberculosis, because of its unique biochemical behavior and a complex host relationship, successfully evades the host immune system. Therefore, chemotherapy appears to be the first-line option for patients with tuberculosis. However, poor patient compliance with anti-tubercular treatment and variability in anti-tubercular drug pharmacokinetics are among the major driving factors for the emergence of drug resistance. The rising cases of extrapulmonary TB, cross-resistance patterns, high prevalence of tuberculosis and HIV co-infections make tuberculosis treatment more complicated than conventional multidrug therapy. Due to their distinct advantages like higher solubility, increased payload, controlled release profiles, tissue-specific accumulation, and lack of toxicity, nanoscale materials have immense potential for drug delivery applications. An appropriate selection of polymer and careful particle engineering further improves therapeutic outcomes with opportunities to overcome conventional anti-tubercular drugs' challenges. The present review introduces the prospect of using nanotechnology in tuberculosis (TB) chemotherapy and provides a comprehensive overview of recent advances in nanocarriers implied for delivering anti-tubercular drugs.

(Solvato-) polymorphism of formulations of rifampicin for pulmonary drug delivery prepared using a crystallization/spray drying process

Rifampicin is an antibiotic used in tuberculosis therapy showing extensive (solvato-) polymorphism. Per oral administration of high doses is recommended, but application as dry powder for inhalation at the site of infection being the lungs, is desirable. Recrystallization from ethanol and consecutive spray drying is reported to yield a rifampicin dihydrate with suitable aerosol performance and stability. Nevertheless, the origin of water in the crystal remained unclear and demanded further investigation so to clarify its solid state throughout manufacture and storage. The present study reports the relationship of (solvato-) polymorphs occurring during manufacture and storage of samples recrystallized and spray dried from ethanol, methanol and water and it was concluded that processes involving a recrystallization from EtOH and MeOH produce particles of a common isostructural group of channel solvates. Samples recrystallized and spray dried from water were identified as members of another isostructural group, which was already characterized in literature. As a second aim, aerosol performance and storage stability of the formulations were investigated and all samples showed stable aerosol performance. Chemical stability of samples spray dried from ethanol was found suitable over a period of six months, whereas samples spray dried from methanol or water showed significant degradation.

Inhalable dry powders of rifampicin highlighting potential and drawbacks in formulation development for experimental tuberculosis aerosol therapy

Introduction: Recently, tuberculosis was reported as the leading cause of death from a single infectious agent. Standard therapy includes administration of four first-line antibiotics, i.e. rifampicin, isoniazid, ethambutol, and pyrazinamide over a period of at least 26 weeks, which in case of rifampicin oftentimes is accompanied by unwanted side effects and variable bioavailability that compromise a positive therapeutic outcome. As the main site of infection is the lungs, it is desirable to develop a therapeutic formulation to be administered via the pulmonary route.Areas covered: This work presents a literature review on studies investigating inhalable dry powder formulations including rifampicin in the context of an experimental tuberculosis therapy, with a special focus on aerosol performance.Expert opinion: It was found that formulation approaches involving different strategies and functional excipients are under investigation but as of now, no formulation has managed to leap into commercial clinical testing. Reasons for this might not primarily be associated with a lack of suitable candidates, but amongst others a lack of suitable in vitro models to assess the efficacy, therapeutic benefit, and cost-effectiveness of the candidate formulations.